Transfer Tool did not update FTP subdomain in DNS zones

I have transferred a few accounts to another server and will be transferring more in the next few days.

In my first batch, the FTP subdomain in the DNS zones were not updated. They are still using the old IP.

(1) Is there an easy way to update the transferred domains' DNS zones? I am doing it manually using WHM - very tedious. I'm using DNS cluster and changes might not propagate to other DNS servers if I modify /var/named files.

(2) How can I permanently fix this issue so it won't happen on my next transfers?